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Synthesis and Study of Linear and Cyclic Polycyclopentadienones and Polypheylenes Robert G

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Synthesis and Study of Linear and Cyclic Polycyclopentadienones and Polypheylenes Robert G University of Vermont ScholarWorks @ UVM Graduate College Dissertations and Theses Dissertations and Theses 2008 Synthesis and Study of Linear and Cyclic Polycyclopentadienones and Polypheylenes Robert G. Potter University of Vermont Follow this and additional works at: https://scholarworks.uvm.edu/graddis Recommended Citation Potter, Robert G., "Synthesis and Study of Linear and Cyclic Polycyclopentadienones and Polypheylenes" (2008). Graduate College Dissertations and Theses. 184. https://scholarworks.uvm.edu/graddis/184 This Dissertation is brought to you for free and open access by the Dissertations and Theses at ScholarWorks @ UVM. It has been accepted for inclusion in Graduate College Dissertations and Theses by an authorized administrator of ScholarWorks @ UVM. For more information, please contact [email protected]. SYNTHESIS AND STUDY OF LINEAR AND CYCLIC POLYCYCLOPENTADIENONES AND POLYPHENYLENES A Dissertation Presented by Robert G. Potter to The Faculty of the Graduate College of The University of Vermont In Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy Specializing in Chemistry February, 2008 ABSTRACT Polyaromatic hydrocarbons (PAH) are useful molecules for supramolecular assemblies and nanoscale electronics materials. Due to their high degree of symmetry and lack of heteroatoms characterization is fairly simple and calculated properties very closely match experimental values. By utilizing a controlled, stepwise synthesis, which enables the regioselective incorporation of solubilizing side chains and electron donating or withdrawing groups, we were able to access many novel PAHs of various shapes and sizes. Using an unprecedented asymmetric protected alcohol-benzyl bromide Collman coupling strategy we have accessed linear oligocyclopentadienones and oligophenylenes not accessible through current methodology. Monomers of these two classes were studied both spectroscopically and computationally in order to fully characterize their electronic structure and see how perturbation of the PAH scaffold affected their respective molecular orbitals. Using a harsher unsymmetrical carbonylative coupling of α,α'-dibromoxylene we were able to access the two previously unknown low molecular weight polymers: Poly(para-phenylene)(2-isocyano-2-tosylpropane-1,3-diyl) (PPIT), and Poly(para- phenylene)(2-oxopropane-1,3-diyl) (PPOD). PPIT and PPOD were demonstrated to be possible precursors of high molecular weight polycyclopentadienones and polyphenylenes. Small macrocycles of these polymers were also produced through the same methodology at high dilution. Conversion of the polymers and oligomers to linear and cyclic polycyclopentadienones and polyphenylenes has been demonstrated in two prototypic examples. While universal methodology for larger oligomers and polymers is still under study, we believe the ultimate goal of discrete isomer carbon nanotubes and linear graphite to be possible due in part by the work reported in this thesis. ACKNOWLEDGEMENTS I would like to thank Prof. Leenstra and Prof. Gordon for sparking an interest in quantum mechanics and group theory. Prof. Madalengoitia was very helpful with questions regarding many of the reactions I encountered over the course of my graduate studies. I would also like to thank Prof. Chu for use of the Physics department computational facility. I learned more from Prof. Hughes in my first year here than in any point in my life. I thank him for his instruction and his patience. Dr. Deker and Dr. Breeyear were my two supervisors in the UVM NMR/MS facility over the past 2 ½ years and I owe a great deal of gratitude to them for their instruction of operation and maintenance of the instruments, as well as the UVM chemistry department for funding me as a teaching assistant through all five years at UVM. I would also like to thank my mother, father, and brother for their constant support throughout the years, and also to my colleagues in the Hughes group for their helpful discussions of chemistry and topics outside. Finally, I would like to thank my wife, Rachel. Part of the ability to tackle a seemingly insurmountable task is to have an unconditional commitment to its completion. It seems odd then that falling in love would have been so integral to the success of my work and of everything that has come together since we first met. It is through your persistent confidence ii and companionship, however that all of this has been possible. This work is dedicated to you. iii TABLE OF CONTENTS Page ACKNOWLEDGEMENTS............................................................................................. ii LIST OF TABLES......................................................................................................... vii LIST OF FIGURES ......................................................................................................viii CHAPTER 1: Polyaromatic Hydrocarbons in Solid State Electronics............................ 1 1.1. Project Overview ................................................................................................... 1 1.2. Electronic Properties of Polyaromatic Hydrocarbons ........................................... 2 1.3. Rm,n Vector Classification of SWCNT Isomers..................................................... 4 1.4. Linear Polyaromatic Hydrocarbons....................................................................... 9 1.5. Synthesis of Hexabenzocoronene as a Template for Synthesis of Many Different Linear and Cyclic Polyaromatic Hydrocarbons.......................................................... 12 CHAPTER 2: Synthesis of Hexaarylbenzenes .............................................................. 19 2.1. Introduction ......................................................................................................... 19 2.2. Carbonylative Couplings ..................................................................................... 19 2.3. Des Abbayes Carbonylative Coupling................................................................. 20 2.5. Collman Carbonylative Coupling........................................................................ 23 iv 2.6. Mechanism of Collman Carbonylative Coupling................................................ 26 2.7. Results of Collman Carbonylative Coupling with Benzyl Bromides.................. 28 2.8. van Leusen Carbonylative Coupling ................................................................... 34 2.9. Knövenagel Condensation: Synthesis of Tetraarylcyclopentadienones.............. 37 2.10. Antiaromaticity of Tetraarylcyclopentadienones .............................................. 39 2.11. Substituted Benzils Through Sonogashira and Friedel-Crafts Reactions.......... 40 2.12. Diphenylacetylenes Through Sonogashira Reactions ....................................... 42 2.13. Diels-Alder Synthesis of Hexaarylbenzenes ..................................................... 47 2.14. Conclusion ......................................................................................................... 50 2.15. Experimental Details ......................................................................................... 50 CHAPTER 3: Molecular Orbital Model of Tetraarycyclopentadienones.................... 108 3.1. Introduction ....................................................................................................... 108 3.2. Background........................................................................................................ 108 3.3. Synthesis of Tetraphenylcyclopentadienone Monomers................................... 112 3.4. UV-vis Spectroscopy of Tetraarylcyclopentadienones ..................................... 114 3.5. Electronic Structure and Electronic Transitions of TACPDs............................ 118 3.6. Correlation of MO energies and UV/vis Spectra............................................... 126 CHAPTER 4: PPIT a Precursor of Linear Graphite. Synthesis of Linear Tetracyclone and Polyphenylene Oligomers ..................................................................................... 135 v 4.1. Introduction ....................................................................................................... 135 4.2. Discovery of PPIT ............................................................................................. 136 4.3. Characterization of PPIT ................................................................................... 137 4.4. Transformations of PPIT to PPOD and Other Previously Unreported Polymers .................................................................................................................................. 140 4.5. PPOD ................................................................................................................. 141 4.6. Small Molecular Weight PPOD Oligomers to Test Multiple Knövenagels...... 143 CHAPTER 5: Aromatic Macrocycle Synthesis: Carbon Nanotube Precursors........... 157 5.1. Introduction ....................................................................................................... 157 5.2. Claisen Condensation Synthesis of Diphenylacetone Dimers........................... 157 5.3. Grignard Reactions for production of Arylacetone Dimers .............................. 160 5.4. Sonogashira Coupling for Production of Phenylene-Propynylene Macrocycles .................................................................................................................................. 162 5.5. van Leusen Coupling of Cyclic Oligophenyleneacetones................................
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